Windows users: this may be the result of a VST cache issue. Create a sub-folder in your VST location, move the UVI Workstation plug-in DLL file there, then rescan your VST locations in the preferences of your DAW. After this you can move the DLL file back to its original location and rescan your VST locations if you would like.

For further troubleshooting, please check the support pages on your DAW’s company website.